The use of roof windows in the roofs of buildings for providing natural illumination in attics or in upstairs living quarters in domestic dwellings and other buildings is well-known.
A roof window assembly within the meaning of the present invention generally comprises a frame which is connectable to a surrounding roof structure. The connection between the frame and roof structure is suitably sealed in order to prevent intrusion of moisture from the roof into the space beneath the roof. A movable sash comprising a window pane is supported with clearance within the frame, usually by way of a pivotal connection.
Any clearance space allowed between the frame and sash for movement of the sash must be covered by suitable means for preventing any intrusion of moisture through this space, at least when the window assembly is in its closed condition. This may be achieved in known fashion by way of complementary flange formations connected to and arranged along the periphery of either the sash or the frame, or both, whereby a substantially weather-proof overlap between the frame and sash is achieved. The flange formations may either form an integral part of the sash and/or frame, as the case may be. Alternatively, sheet metal flashing may be connected to the sash and/or frame in order to overlie the clearance space between the sash and frame. Rotation of the sash in relation to the frame is usually limited, however, to approximately 90.degree., by reason of the interference of the flange formations or flashing with adjacent portions of the window assembly.
This limitation is overcome at least partially in a roof window assembly known to the applicant in which externally mounted pivotal connections are provided between the frame and sash. Each connection is located adjacent to an overlapping joint between a portion of flashing secured to the sash and a further complementary portion of flashing secured to the frame. This arrangement allows the sash to be rotated through an angle in excess of 90.degree. about its pivotal axis while allowing the flashing connected to the sash to pass with clearance underneath the flashing of the frame when the assembly is in its closed condition. This assembly has the disadvantage, however, of leaving the pivotal connections exposed to the prevailing weather conditions, leading to their eventual deterioration.
In yet a further roof window assembly known to the applicant the pivotal connections provided between the sash and frame, are displaceable along tracks whereby the sash is outwardly displaceable in relation to the frame in order to provide sufficient clearance between the flashing of the sash and frame for rotation of the sash through angles in excess of 90.degree.. The track portions and the components co-operating with these must be manufactured and fitted with relatively close mechanical tolerances, which makes this type assembly comparatively expensive.
It is an object of this invention to provide a hinge for use in a roof window assembly of the kind described above having relatively few components while allowing unimpeded rotation of the sash through an angle of at least 90.degree..
It is a further object of this invention to provide a roof window assembly having flashing for providing a weather-proof seal between its frame and sash, in which a portion of the flashing secured to the sash is allowed to pass with clearance underneath a portion of the flashing secured to the frame whenever the roof window assembly is brought towards its closed condition.